The new Canadian fluoride-IQ study has certainly created some sensational reporting. On the one hand, anti-fluoride campaigners are lauding the study as the best things since sliced bread and seem sure it will lead to the end of community water fluoridation. Mainstream media have featured the findings – although in most cases warn they are controversial and may be meaningless. As would be expected, alternative health media have been promoting it and repeating the anti-fluoridation arguments.
However, scientific commenters have mainly criticised the study and warned that even if the findings are valid it is just one study and it is far too early to consider stopping community water fluoridation – a health policy which is so far been seen as economical, safe and effective in helping fight tooth decay.
I strongly believe the scientific critiques are important. One should not rely on “authority” statements in such matters – especially statements from well known anti-fluoride activists. But we should also be aware that self-promotion by the authors and journal, and by the authors’ institutions, is also not a reliable indicator of the worth of a study.
In the end, the validity and worth of this study will depend on the data and methodology – and good scientific critiques will look at these, not the status of the journal, institutions or authors. And not the public statements being made to promote the findings.
Some interesting critiques are coming from Dr. René F. Najera who is a Doctor of Public Health, an epidemiologist and biostatistician. These are the very skills essential for a proper critique of the Canadian study.
The specific study Dr. Najera refers to is:
Green, R., Lanphear, B., Hornung, R., Flora, D., Martinez-Mier, E. A., Neufeld, R., … Till, C. (2019). Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada. JAMA Pediatrics, 1–9.
For my other comments on the Candian fluoride/IQ research see:
- If at first you don’t succeed . . . statistical manipulation might help
- Politics of science – making a silk purse out of a sow’s ear
- More expert comments on the Canadian fluoride-IQ paper
- An evidence-based discussion of the Canadian fluoride/IQ study
The “shenanigans” of activists
In his first article, The Hijacking of Fluorine 18.998, Part One, Dr. Najera gives some background. He says:
“Time after time, epidemiological studies have shown that fluoridated water leads to less tooth decay. Less tooth decay leads to better health outcomes as poor oral health is a risk factor for a variety of conditions. At the same time, all of these studies failed to see any association between bad outcomes and fluoridation done correctly.”
” . . those people who were suspicious of putting fluoride in the water did what people who are suspicious of public health interventions often do: they heard of some bad outcome of ingesting fluoride (which is a compound made up of fluorine, the chemical element), amplified it, exaggerated it and showed it as the ultimate example of what fluoride consumption at any concentration can do to a person.”
He compares this to “the shenanigans of the anti-vaccine crowd” and concludes that:
“…just like we had to do in the late 1990s with the Wakefield Fraud “study” that was not a study, here we go fighting a new fight against misinformation…”
He concludes this because:
“In consultation with friends and colleagues, we found a lot to be worried about in the epidemiological design of the study and the biostatistical analysis of the resulting data… And, of course, of the conclusions reached by the authors and the press (with some help from the authors). “
Some epidemiological concerns
In his second article, The Hijacking of Fluorine 18.998, Part Two, Dr. Najera expresses his epidemiological concerns about the research. These include:
1: Unwarranted exclusion of some mother-child pairs:
“For example, some were excluded because they did not drink tap water or lived outside a water treatment zone. Wouldn’t you want to know if not drinking tap water or living outside a water treatment zone led to children with normal-to-high IQs compared to the others?
This raised flags with me because I don’t exclude someone from an outbreak investigation if they don’t have a desired exposure. In fact, I want to know if someone who is not exposed to something is less likely to develop the disease or have the condition I’m studying. It would be like saying that I don’t want women who live in air-conditioned apartments in a city included in a study on Zika because they are not likely to have been exposed to mosquitoes like women living in huts in the jungle.”
2: Overlap of groups:
“In the end, they had 369 mother-child pairs with mean urine fluoride (MUF) measurements, IQ measurements and water fluoride data and 400 mother-child pairs with fluoride intake and IQ measurements. But that’s 769 pairs when 610 children were originally considered? Yes, there is some overlap between the two groups. No big deal if they do their biostats right. (Spoiler alert for Part Three: They didn’t.)”
3: Urinary fluoride data questionable:
“They then used data on mean urine fluoride concentrations from spot (one-time) urine samples taken at different points in the mothers’ pregnancies, and they only accepted those who had been tested throughout (i.e. didn’t miss a test). The problem with this is that the standard to really know how much fluoride someone is exposed to — by testing their urine — is a 24-hour collection of urine. In that test, you have someone collect their urine for 24 hours and then we measure the fluoride (or a lot of other chemicals) in that sample. This is because urine concentrations of chemicals vary throughout the day. If you drink a lot of fluoridated water in the morning, then your urine is likely to have higher concentrations shortly thereafter than in the evening, when you’ve been drinking bottled water without fluoride. Or, if you worked out in the morning and drank energy drinks but stuck to only tap water in the evening, your urine fluoride will be different.”
Other scientific commenters have also been critical of the urinary fluoride data. Dr F. Perry Wilson suggests that blood plasm fluoride would have been a far better indicator of fluoride intake (see More expert comments on the Canadian fluoride-IQ paper).
The World Health Organisation’s (WHO) recommendations on the monitoring total fluoride intake for populations also stress the need for 24-hour collection and warn that “urinary fluoride excretion is not suitable for predicting fluoride intake for individuals.” [WHO’s emphasis] (see Anti-fluoridation campaigner, Stan Litras, misrepresents WHO).
WHO recommends it only for monitoring fluoride intake of groups of people because of the large effects of individual diets (see Basic Methods for Assessment of Renal Fluoride Excretion in Community Prevention Programmes for Oral Health). But in this Canadian study, urinary fluoride values were used to estimate individual intake of fluoride.
4: Fluoride intake assessed via an unvalidated survey:
“This means that it is hard to know if the survey really measures what it is supposed to measure. Still, they used it, and it leaves the study wide open to recall bias, something you want to minimize as much as possible. And they would have minimized it if they used it a more valid survey, or a prospective design to their study.
First, what is a prospective design? Well, this is when you take a group of women and sign them up for the study, then you carefully measure their fluoride intake with more validated laboratory assays and questionnaires, and then you follow their children and measure their IQ periodically. You don’t do it all retrospectively with already collected data. But, sometimes, what you have is what you have.
Next, what is recall bias? Recall bias is this interesting phenomenon we see when we rely on people telling us their story in order to ascertain risks and outcomes of exposures. We epidemiologists have noticed that people who have bad outcomes tend to be more likely to remember significant exposures. For example, parents of children with birth defects are more likely to remember things like exposures to chemicals or a history of disease in the family. While parents of typical children don’t recall similar exposures as much because, well, they aren’t looking to connect any dots.
(You see this all the time in anti-vaccine circles, where parents of autistic children are more likely to recall bad reactions to vaccines in their children.)”
Dr. Najera also finds this methodology strange because “they multiplied the intake of certain drinks by some factors in order to estimate fluoride intake:”
“This complicates things because, as you saw above, they excluded women who were not in places where the water was being treated and women who didn’t consume tap water. But, come on, have you ever met someone who never consumed tap water? Do we not use tap water to cook foods all the time? What about that fluoride intake? And why just multiply for fluoride in beverages and not, say, that delicious Canadian cheese soup I’ve heard good things about?”
5: Problems with IQ testing of children:
“I’ve asked some friends of mine who are experts in childhood development, and they are skeptical of accurate measurements of IQ in children because children develop at different rates depending on a variety of variables. You may have seen this when you look at a classroom or a school play. Children are on a big spectrum of development, with milestones being really more like average moments.”
6: Sample not representative:
“The sample used in this study is not at all representative of all mothers and their children in Canada, not even close. As we saw in the paper, many women were left out of the study for a variety of reasons, and mother-child pairs were also excluded. I want to believe that there were good reasons for this, but I could not find them in the paper. The authors do mention that they wanted to look only at mothers consuming fluoride, but why not include those who were not expected or outright did not consume fluoride in order to really compare two populations of interest?”
Dr. Najera finishes with a general comment about the way other studies in the scientific literature are used to provide credibility to the findings;
“Finally, the authors mention other studies — some with rats, other purely environmental — where there is some association between fluoride intake and lowered IQ or some sort of negative impact to neurodevelopmental delay. The thing is, public health agencies around the whole world have been looking at these claims and not finding them to be true within their populations. “
I also find the practice concerning, especially as it is relatively common. I think it indicates confirmation bias – the authors making citations that they think support their findings (and purposely refraining from citing studies that don’t). I find this practice disingenuous because it never qualifies the citations with any reference to the applicability to the real-life situation of community water fluoridation. It never points out the high fluoride concentrations used in animal studies or the fact that many research articles on fluoride and child IQ have involved populations in areas of endemic fluorosis where health problems abound.
Dr. Najera is planning a third article discussing the biostatistical issues with the research – a very important issue I have commented on in previous posts. I look forward to it and will do a post on it in due course.
I responded with science and looks like my post was removed. Probably the same result with this post, but let me try.
The Fluoride Action Network cites 454 studies on fluoride’s neurotoxicity. 68 human studies of which 61 reported harm.
CDC does not list any on their website.
ADA lists 19, all but one is in Fluoride Facts only available by purchase. (ADA knows how to make money on fluoride!)
American Academy of Pediatrics lists 4
American Fluoridation Society lists 13.
As researchers understand those most at risk, they are focusing their research and reporting harm at ever lower fluoride concentrations and exposure.
What fluoride exposure prevents dental caries? Silence, because the question has no scientific answer.
What fluoride exposure are you and your family getting? Unknown
What fluoride exposure is safe for everyone, not just the 90th percentile, but everyone?
Ken, you need to look at the big picture. Science is stacking against excess fluoride exposure and many are ingesting too much fluoride.
Fried brains are not cheap on society. Increased special education in schools, increased parental time, lower success in work, lower income, greater frustration in school and work.
Fluoridation is causing a significant increase in the number of mentally retarded and many fewer gifted.
Fluoridation must stop.
Bill Osmunson DDS MPH
Bill, no post of yours has been removed. Might I suggest you have made a mistake – or are you misrepresenting a situation in the same way you have knowingly lied about your inability to participate in the scientific exchange I have offered you here. How do you sleep at night when you tell people on other forums that I have blocked this exchange when, in fact, it is you who has refused to follow through with the formatting and references asked for.
It is extreme naivety to talk about numbers of toxicity studies without any critical assessment of these studies. Do you know there are far more studies about the toxicity of water or chloride than there are about fluoride (see Approaching scientific literature sensibly)?
Of course, each study must be assessed on its own merit – this requires looking at the data, not relying on opinion. You have agreed that the recent Green et al (2019) shows no effect of fluodiation on a child’s IQ – as I have pointed out in my posts. Yet you will still list this as one of your “68 human studies.”
If you are unable to critically assess any of these studies becuase you don’t understand the chemistry or statistics then you have absolutely no right to talk about looking “at the big picture.” After all, the process you are demonstrating would lead us to conclude that we should stop drinking water because of the “big picture” showing such toxicity.
Bill, you say, “The Fluoride Action Network cites 454 studies on fluoride’s neurotoxicity. 68 human studies of which 61 reported harm.
“CDC does not list any on their website.”
I asked Kip Duchon at the CDC about a similar question a few years ago. This is our exchange in full:
“Hello Mr. Duchon,
“I recently read this quote, from Dr. Paul Connett, referring to the Fluoride Action Network’s fluoride database: “However, our health database on fluoride’s toxic effects and the potential for fluoridation to cause harm is second to none. It is larger and more inclusive than any database maintained by health agencies promoting fluoridation. One only has to check out the section on fluoride and the brain to see just how comprehensive it is.”
“Do you believe this is true?
“Thank you for your time.”
“I have no personal knowledge of their database, but I would mention that there are a lot of papers that have been published that claim some harm, but they are not peer reviewed and have confounding issues. If they include all those discredited publications, then it may be true that they include more references, for the National Academy of Sciences, EPA, and CDC only use peer reviewed and articles that have not been found to have confounding issues or otherwise discredited by subsequent followup studies.
“Kip Duchon, P.E.,
Centers for Disease Control and Prevention
National Fluoridation Engineer”
First to David, then Ken.
Kip Duchon is an engineer and excellent at designing equipment if you want to carefully add fluoride to your public water. However, David, we are discussing neurotoxic effects of fluoride, not the best fluoridation equipment.
Duchon is not an epidemiologist, toxicologist, neurologist, nutritionist, dentist or MD. In effect David, you are changing the subject from “poison” to “plumbing.” Don’t expect your plumber to be the expert on toxic substances , dosage, or benefit safety evaluation.
May I request David, that you read or review some or all of the 454 studies on fluoride’s neurotoxicity and let me know which ones are not peer reviewed? Almost all are, from what I’ve read. Duchon is wrong and ignorant on the toxicology research, but he is the expert on equipment engineering. We are not discussing engineering here, we are discussing neurotoxic effects of excess fluoride exposure. Likewise, I am ignorant on the fluoridation equipment.
And yes, FAN has more studies on fluoride’s neurotoxic effects than the Library of Congress or any other data base. FAN has translated peer reviewed published studies from other languages. Both English and other languages (translated) are available on the FAN site. . . at no charge. (Unlike the ADA which likes to profit from fluoride.) FAN is dedicated to helping each person find the best available science for their review. You should read the studies, as Paul Connett and I suggest.
Now to Ken. Looks like I got under your skin. Name calling is not professional.
Yes, I made a very careful response to your blog and posted it. Maybe it will show up from cyberspace some day.
In the mean time Ken, I am not a liar. You wanted a discussion on an aspect of fluoridation which I am not an expert and for which judgment needs background. Dosage comes first.
In both my Master’s program and doctoral program and every day as a clinician, dosage is at the foundation of judgment. Until we establish dosage, we are not talking the same language nor are we able to have adequate judgment.
For example, we would both agree water is essential for life and yet too much can be lethal. How much is needed, how much is too much, and what is the range of safe dosage? Until the most basic fundamental questions are asked and answered any judgment of water’s efficacy and safety. . . “dosage” can be problematic.
Yes, Ken, I agreed to discuss fluoride’s neurotoxicity but first we need some basics of ground work on dosage. All good scientists would agree. Dosage. judgment on harm must have a foundation of how much of the substance are we talking about.
You refused. Why? Because there are no good studies on dosage, mostly marketing, “mythology” and tradition. After 70 years of forced medication, proponents, my professions of dentistry and public health are essentially clueless on dosage. My professions say “safe and effective” but they don’t know how much a person is ingesting, how much is beneficial (if any) and how much is harmful.
For judgment, one must start with the basics of how much do we want for an individual, how much is effective, how much are they already getting and how much needs to be supplemented and finally how much is too much.
Ken, I’m asking again, how much fluoride should each person ingest to “prevent” dental caries?
Bill Osmunson DDS MPH
I agree that the number of studies is only one factor to consider and the quality of the studies is far more important. I would also say the lack of studies could be even more important. The lack of quality studies on efficacy should keep you up at night. But you don’t want to consider the absence of evidence, the missing pieces, the poor quality where we can have good quality. Those concerns don’t fit into your bias.
Further, I do not say ” that the recent Green et al (2019) shows no effect of fluodiation on a child’s IQ.” Don’t put words in my mouth. When I read the study first, I had the same concerns you raise. I was clear I had concerns at first. On closer review, the Green study does find a neurotoxic effect. I explained in another post.
And then you assume that like the CDC, ADA, et al, we only have studies on one side of the neurotoxic issue. FAN does not cherry pick studies, exclude studies, to market an opinion. FAN includes all studies. The vast majority of published studies, but not all, show harm. You say, ” Yet you will still list this as one of your “68 human studies.”
Hang on Ken. Are you implying that the Green study was not on humans? Of course it was. Your statement assumes FAN only lists studies reporting harm. Just not true. FAN lists all studies so you can decide where the evidence stacks up.
The point I am trying to make is the Green study is not the only study reporting harm and there are some which did not find harm. As we understand more about the effects of fluoride on the neurologic development, researchers pick the areas which seem to have the most concern.
The US Government funded the Green study. HHS/CDC do have some oversight of where the money is going and expectations for scientific results.
The Green study conclusions are correct. Don’t distort the data.
Bill Osmunson DDS MPH
Bill, I am not indulging in name-calling with you. I am simply pointing out that you have lied about our proposed scientific exchange. You continue to avoid this and do not apologize for that lie which indicates you will not participate in normal good faith scientific exchanges.
I invited you to have this exchange and am more than willing to proceed with it seeing you wanted to discuss the fluorosis issue and recent data on dental fluorosis prevalence. You provided a pdf for your initial contribution – I asked for it to be formated in Word to enable me to put it into the blog format (this is not a simple as copy and past from a pdf). I also asked for the citations and links for references and corrections of a figure. You have not responded to this (despite indicating you would) and have since told others that I have refused to proceed with the exchange.
That is simply dishonest and until you apologize and withdraw the lie I can see no value in any exchange with you.
You are repeating this pattern by implying again that I have deleted a discussion post from you. I have not. You may have made a mistake – if so you will repost but until then I cannot believe anything you say about that.
You say “I responded with science and looks like my post was removed” but, Bill, you are simply not known for being proficient in the science area. The fact is you agreed with me that the Green et al study found absolutely no effect of fluoridation on child IQ in that the mean IQs for children from mothers who had resided in fluoridated and nonfluoridated areas were exactly the same. The authors refused to discuss this fact and no amount of playing with statistics to obtain weak relationships has changed that fact. (Their relationship was with a shonky measure of maternal urinary fluoride – not with fluoridation.)
So Bill, stop this slandering of me, admit you lied about our exchange and show some respect for your discussion partner.
I never lied. You are slandering me and must stop.
I agreed to your blog but we must start with basics because you are clueless on dosage. I am not your whipping dog or slave. And I am not a liar. I have said yes, but dosage first. . . post after post after post.
Don’t call me a liar when you refuse to agree to the subject matter.
Bill Osmunson DDS MPH
Bill you have lied – and you know it because it has been discussed already.
On the AARP forum you referred to my offer of good faith scientific exchange by saying this:
That was a complete lie – you know that because we had an email exchange when I asked you to provide references and citations and links and to correct a figure.
I responded to that lie on the AARP forum by quoting from the actual email exchange. Here is the text of my reply:
I do not appreciate your misrepresentation of the situation or your attempt to imply I am avoiding any exchange. For this reason, I will quote from our emails and I apologise for the length.
These emails followed my offer of an open uncensored exchange on my blog along the lines of the one I had with Paul Connett in 2013/14. You accepted my offer and on April 5 this year I got a document with your email saying:
“Here you go, attached. Graphs did not cut and paste below.
Excess Fluoride Exposure—Streams of Evidence
I responded the same day with:
“Thanks for this Bill.
“I will aim to start this exchange early next week (Weekends are not a good time for hits). I should be able to extract the images from the pdf.
Do you have a reference list to go with this that could go at the end of the article?”
I set out to make the necessary conversions to unformatted text required on the blog but had some difficulties and emailed you 2 days later (April 7) saying:
Do you have a word version of this?
I am having trouble removing the formatting when converting the pdf so a word or text version would help.
Also, have you got a reference or citation list yet – preferably with links.”
You replied the next day (April 8):
“Working on it.
And then later
“**bleep** computers. I also had problems and I’m moving and swamped. I did add some references. Can you get it off of this attachment?
On April 10 I replied:
I think I can just copy and paste from the pdf and I have extracted the figures. But have not yet been able to extract a reference list from what you gave me.
But now my computer is now playing silly buggers and it is undergoing a long term scan – probably not complete until tomorrow (when I have my great grandson for our weekly play date so won’t be doing any computer work).
It would help if you could extract the references and give me a list, preferably linked, that I can add to the end of the article.
Then my computer packed up. It was taking a while to repair (both hard drives were wiped) so I contacted you a few days later (April 15):
My computer is being repaired. Learned yesterday that both hard drives have been wiped. I do have a backup but it will take time to reinstall all the programmes and recover the data.
So anything you can do to insert the references and links will help.
Don’t know when I will get the computer back. They may well find other problems.
You responded on April 17
“Sorry about computer problems.
I’ll see what I can do. How do you want references inserted? Footnotes is what I provided. Do u want web links instead?”
I cannot, at this time, find any of our other correspondence on this specific issue.
However, I had given up hunting down your references (yes proper citations and links are normal – out of respect to readers and to you discussion partner. How can one check what the referenced article says without proper citation?).
There was also the problem of a figure which had not been prepared properly for this particular exchange (Obviously used elsewhere).
But I certainly understood the ball was in your court to correct the article (as it should be) and in no way was I withdrawing from the exchange.
As I explained the other day I am interested in critiquing the dental fluorosis argument – specifically the Neurath paper you rely on in your article – so I am keen for the exchange to go ahead.
I hope this clarifies the situation for other readers. I repeat I do not appreciate the misrepresentation you have indulged in, Bill, or the resort to abusive terms. These should not be used in a scientific exchange – another reason why I think the Open Parachute blog is the best place for such an exchange.
So, yes Bill, you have lied and an apology is needed.
Bill says, “Duchon is not an epidemiologist, toxicologist, neurologist, nutritionist, dentist or MD.”
Hilarious. One of Paul Connett’s major grievances against the Oral Health Division of the CDC was that they were nothing abut a bunch of dentists.
Perhaps I have been too complex so let me use myself as an example..
I swallow an estimated 2.8 mg of fluoride a day.
Recommended dosage is zero mg of fluoride a day.
What dosage of more fluoride do you recommend public health officials use police powers to force me, without my consent, to swallow?
So let me explain further. Individual intake is an estimation, not measured. How much fluoride do you swallow every day?.
Theoretical benefit of swallowing fluoride is up to age 8 while the tooth is developing under the skin. My teeth are all developed so swallowing fluoride will not help my teeth. And if a person does not have teeth, obviously, no benefit.
You provide no evidence I lied.
Fact: you have not published my article on dosage, first excuse was computer problems (probably valid) and second formatting. If I spent the time to format you probably would not publish so I will not waste my time.
Fact: you have not published any evidence, let alone scientific, on dosage (which I have seen). There really is no good scientific evidence on dosage, so I’m asking a question which with the evidence we have is not really answerable scientifically. Yet the question is at the heart of what you have staked your reputation on. Namely, that I need more fluoride.
And Randy, please provide a direct complete quote from Dr. Connett. I have not heard him say what you claim he said. I have heard him say, “mostly dentists.” I understand the director of the Oral Health Division is/was a lawyer. I have not heard Dr. Connett say “all” at the CDC OHD are dentists.
Bill Osmunson DDS MPH
Bill, here are some undeniable facts.
1: You said on that other forum”
That is you were claiming that I had not followed through with my offer.
In fact, our email exchange (listed in my previous comment) showed that to be a complete lie.
2: Now you agree that there was an exchange related to formatting, citations and one of the images. You acknowledge that in your statement:
Of course requests for citations, formatting, and images were no excuse – how childish can you be?
But that is it – you have said two contradictory things. You have lied and you wish to put it back on my by claiming I would not post your article by saying:
Come on. I welcomed this exchange – it would have given me a chance to deal with Neurath’s paper. And do you really think I find your arguments so intimidating after having deal extensively with Paul Connett’s arguments?
You lied and did so in a childish way. You have effectively pulled out of this offered exchange.
May I remind listeners that this is nti the first time you have withdrawn for an exchange on this blog. This is outlined in my blog posts Do we need a new fluoride debate? and New fluoride debate falters.
Bill, you are completely unreliable and untrustworthy. Of course, there will not be a scientific exchange with you because you are incapable of such a good-faith discussion.
You are name calling, “childish” “liar” and attack me because you do not have science to back your mythology and barbaric support of forced mass medication.
You refuse to answer with science because you lack facts and evidence.
Dosage. How much. Think, my friend. Use your head and not blind bias.
Bill Osmunson DDS MPH
Bill, I am not calling names – simply describing your behavior.
You lied about the scientific exchange claiming I had stopped it when it was you that pulled out.
Saying that you pulled out because I probably wouldn’t post your contribution is simply a childish excuse.
So if I use the terms, dishonest, liar, pervert, bully, idiot, brain dead, childish, senile, crazy, stupid criminal, failure, . . . I’m not name calling, just describing your behavior? Really Ken. You make no sense. Those terms are name unprofessional and should not be used.
You have my article. You could publish, but you chose not to. I did not pull out. You have it. You never published it or your response.
You avoid dosage because that rabbit hole will turn any good scientist against adding more fluoride to anyone’s diet.
Instead you spend time attacking me instead of the science. When that happens, the defense of fluoridation is lost.
Too many are ingesting too much fluoride. Adding more borders on a criminal act.
Bill Osmunson DDS MPH
Ken, Look up the definition of AD HOMINEMS.
“directed against a person rather than the position they are maintaining.”
Personal labels are inappropriate in the context of any discussion that is trying to find viable solutions.
When the person is attacked rather than the subject, solutions will be hard to come by.
Bill Osmunson DDS MPH